Optical lens, image-capturing device and optical touch system

ABSTRACT

An optical lens is configured in front of an image-capturing lens of an image-capturing device. A light-emitting unit of the image-capturing device emits a light beam. The optical lens includes a pair of peripheral compensation portions and a central diverging portion. Each peripheral compensation portion has a first convex surface and a first concave surface arranged opposite to the first convex surface. The central diverging portion is arranged between the peripheral compensation portions, and has a second concave surface and an oppositely arranged light incident surface. The second concave surface is arranged between the first convex surfaces. The light incident surface is arranged between the first concave surfaces. The optical axis of the light beam sequentially aligns with the light incident surface and the second concave surface. The light rays of the light beam pass through the first concave surface and the first convex surface in sequence.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The instant disclosure relates to a touch system and the components ofthe touch system; in particular, to an optical lens and animage-capturing device applied in an optical touch system.

2. Description of Related Art

The existing touch control technology has already developed an opticaltouch system. The optical touch system commonly includes a plurality ofimage sensors and a plurality of infrared light emitting diodes (IRLEDs), in which the IR LEDs for example can be complementary metal-oxidesemiconductors (CMOS) or charged-coupled devices (CCD).

The optical touch system has a contact plane for an object to makecontact with. During the operation of the optical touch system, the IRLEDs emit infrared beams which are transmitted via the contact plane.When an object such as a finger or a stylus touches the contact plane,the object will block a certain number of infrared beams. As a result,shadows are generated on the contact plane. Meanwhile, the image sensorscan detect the shadows. The optical touch system can use the shadows tocalculate the position of the object on the contact plane and to furtherprovide touch control.

SUMMARY OF THE INVENTION

The object of the instant disclosure is to provide an optical lens usedfor an optical touch system which has a plurality of image-capturingmodules and a plurality of light-emitting units. The optical lens canchange the view angle of the image-capturing module and the distributionof the light intensity of the light-emitting unit.

The instant disclosure also discloses an image-capturing device whichincludes the aforementioned image-capturing modules, light-emittingunits, and optical lens.

The instant disclosure also discloses an optical touch system with theapplication of the aforementioned optical lens.

An embodiment of the instant disclosure discloses an optical lens whichcan be configured in front of an image-capturing lens of animage-capturing device. A light-emitting unit of the image-capturingdevice can emit a light beam. The optical lens includes a pair ofperipheral compensation portions and a central diverging portion. Eachperipheral compensation portion has a first convex surface and a firstconcave surface arranged opposite to the first convex surface. Thecentral diverging portion is arranged between and connected to theperipheral compensation portions. The central diverging portion has asecond concave surface and a light incident surface opposite to thesecond concave surface. The second concave surface is arranged betweenthe first convex surfaces. The light incident surface is arrangedbetween the first concave surfaces. The optical axis of the light beamsequentially passes through the light incident surface and the secondconcave surface. The light rays of the light beam pass through the firstconcave surface and the first convex surface in sequence.

In another embodiment of the instant disclosure, an image-capturingdevice is disclosed. The image-capturing device includes animage-capturing module, a light-emitting unit, the aforementionedoptical lens and a casing. The image-capturing module includes animage-capturing lens. The light-emitting unit is fixed at theimage-capturing module and can emit a light beam. The optical axis ofthe light beam and the optical axis of the image-capturing lens bothpass through the light incident surface and the second concave surfacein sequence, whereas a plurality of light rays of the light beam passesthrough the first concave surfaces and the first convex surfaces insequence. The casing includes a frame and a fixing member. The framehousing the optical lens and exposing the first concave surface, thefirst convex surfaces, the light incident surface and the second concavesurface. The fixing member is connected to the frame and fixing theimage-capturing module.

In another embodiment of the instant disclosure, an optical touch systemis disclosed. The optical touch system includes a panel, a plurality ofthe aforementioned image-capturing devices and a processing unit. Thepanel has a flat surface, and the plurality of image-capturing devicesis configured at the periphery of the panel. Each image-capturing moduleof the image-capturing device can capture at least one image data of anobject disposed on the flat surface of the panel to generate acorresponding image signal. The processing unit receives the imagesignal and generates a coordinate signal corresponding to at least oneobject.

With the peripheral compensation portions and the central divergingportion, the optical lens of the instant disclosure can be applied tothe optical touch system to change the view angle of the image-capturingmodule. Moreover, the peripheral compensation portions and the centraldiverging portion can change the traveling direction of the light raysfrom the light-emitting unit such that the optical lens can change thelight intensity distribution of the light-emitting unit.

In order to further understand the instant disclosure, the followingembodiments and illustrations are provided. However, the detaileddescription and drawings are merely illustrative of the disclosure,rather than limiting the scope being defined by the appended claims andequivalents thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a perspective view of the image-capturing device illustratingan embodiment according to the instant disclosure;

FIG. 1B is an exploded view of the image-capturing device as illustratedin FIG. 1A;

FIG. 1C is another perspective view of the image-capturing device asillustrated in FIG. 1A;

FIG. 2 is a front view of the optical lens as illustrated in FIG. 1B;

FIG. 3A is a front view illustrating the lens which is used to make theoptical lens in FIG. 2;

FIG. 3B is a rear view of the lens as illustrated in FIG. 3A;

FIG. 4 is a top view of the image-capturing device as illustrated inFIG. 1A after the disassembly of the casing; and

FIG. 5 is a top view of the optical touch system illustrating anembodiment of the instant disclosure.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1A is a perspective view of an image-capturing device 100illustrating an embodiment according to the instant disclosure, and FIG.1B is an exploded view of the image-capturing device 100 as illustratedin FIG. 1A. Please refer to FIGS. 1A and 1B. The image-capturing device100 has a wide range of application such as for an optical touch system.The image-capturing device 100 can emit a light beam and capture atleast one image data of an object. The object may be a finger or astylus which operates the optical touch system, and the image data canbe shadows created by the object blocking part of the light beam.

The image-capturing device 100 includes an image-capturing module 110, alight-emitting unit 120, an optical lens 200 and a casing 130. Theimage-capturing module 110 includes an image-capturing lens 112 with animage sensor such as a CMOS or a CCD. Thus, the image-capturing module110 can receive light rays from the image-capturing lens 112 and captureimages.

The light-emitting unit 120 is fixed at the image-capturing module 110.For example, the light-emitting unit 120 can be coupled and fixed ontothe image-capturing module 110 via adhesion, screwing, or fasteningmechanisms. The light-emitting unit 120 may be a light emitting diode(LED) which emits light rays such as invisible light (for example:infrared light). Thus, the light-emitting unit 120 can be an infraredLED. Moreover, light rays emitted from the light-emitting unit 120 mayalso be visible light.

The optical lens 200 and the image-capturing module 110 are both coupledto the casing 130 such that the optical lens 200, the image-capturingmodule 110, and the casing 130 are combined together. The casing 130 mayinclude a frame 132 and a fixing member 134. The frame 132 houses theoptical lens 200. In other words, the optical lens 200 is disposed inthe frame 132. The fixing member 134 is connected to the frame 132 andfixes the image-capturing module 110. For example, the fixing member 134may be incorporated with the frame 132. The casing 130 can be made ofmaterials such as plastic, metal, or ceramic. The fixing member 134 andthe frame 132 can be integrally formed. For example, the casing 130 canbe formed by mold-injection, machine-stamping or extrusion. Via thecasing 130, the optical lens 200 can be configured in front of theimage-capturing lens 112 such that the image-capturing lens 112 cancapture images from the optical lens 200.

The optical lens 200 includes a central diverging portion 210 and a pairof peripheral compensation portions 220. The central diverging portion210 is arranged between and connected to the peripheral compensationportions 220. Each of the peripheral compensation portions 220 has afirst convex surface 224 and a first concave surface 222 arrangedopposite to the first convex surface 224. The central diverging portion210 has a second concave surface 214 and a light incident surface 212arranged opposite to the second concave surface 214. Moreover, thesecond concave surface 214 of the central diverging portion 210 isarranged between the first convex surfaces 224 of the peripheralcompensation portions 220, and the light incident surface 212 of thecentral diverging portion 210 is arranged between the first concavesurfaces 222 of the peripheral compensation portions 220. Besides, thesecond concave surface 214 may be connected to the first convex surfaces224, whereas the light incident surface 212 may be connected to thefirst concave surfaces 222.

The light incident surface 212 of the central diverging portion 210 maybe a flat surface or a concave surface. The curvature of the lightincident surface 212 may be larger than the curvature of the secondconcave surface 214. That is, the degree of the light incident surface212 curving may be larger than the degree of the first convex surface224 curving. The curvature of the first convex surface 224 may besmaller than the curvature of the first concave surface 222 in the sameperipheral compensation portion 220. In other words, the curvature ofthe first concave surface 222 may be larger than the curvature of thefirst convex surface 224.

Due to both the first concave surfaces 222 and the first convex surfaces224 of the peripheral compensation portions 220 and both the lightincident surface 212 and the second concave surface 214 of the centraldiverging portion 210, each the peripheral compensation portion 220 hasa first focal length, and the central diverging portion 210 has a secondfocal length. The first focal length and the second focal length areless than zero. In other words, the first and second focal lengths arenegative values. Thus, the optical lens 200 facilitates the light beamto spread and to travel towards the second concave surface 214.

The fixing member 134 of the casing 130 in the instant embodiment mayalso include a pair of fixing strips 134 a. The image-capture module 110is fixed between the fixing strips 134 a. Specifically, each fixingstrip 134 a has a fixing end E1 and a coupling end E2 opposite to thefixing end E1. The coupling end E2 is connected to the frame 132. Theimage-capturing module 110 is fixed between the fixing ends E1. Thefixing ends E1 can directly clamp the image-capturing module 110.Alternatively, the fixing ends E1 can be coupled to the image-capturingmodule 110 via adhesives.

FIG. 1C is another perspective view of the image-capturing device 100 asillustrated in FIG. 1A. Please refer to FIGS. 1B and 1C. The frame 132exposes the surfaces of the optical lens 200, and the surfaces are thefirst concave surfaces 222, light incident surface 212, first convexsurfaces 224, and the second concave surface 214. Specifically, theframe 132 has a light exiting opening H1 and a corresponding lightentering opening H2. The light exiting opening H1 and the light enteringopening H2 expose the surfaces of the optical lens 200. Namely, thelight exiting opening H1 exposes the first convex surfaces 224 and thesecond concave surface 214, whereas the light entering opening H2exposes the first concave surfaces 222 and the light incident surface212.

Please refer to FIGS. 1A and 1C. The light entering opening H2 isarranged between the coupling ends E2. The fixing strips 134 a extendfrom the periphery of the light entering opening H2. The light-emittingunit 120 has an optical axis A1. The image-capturing lens 112 of theimage-capturing module 110 has an optical axis A2. As illustrated inFIGS. 1A and 1C, the optical axis A1 and the optical axis A2 aresubstantially parallel. Thus, the optical axis A1 and the optical axisA2 are substantially in the same plane. In the preferred embodiment, theplane, in which both of the optical axes A1 and A2 are in, can be normalto the horizontal plane. Moreover, the optical axis A1 and optical axisA2 both pass through the light incident surface 212 and the secondconcave surface 214 in sequence.

Furthermore, each fixing strip 134 a can extend in a direction neitherparallel nor normal to the optical axes A1 and A2. The extendingdirection of the fixing strip 134 a represents the alignment thereof. Inorder words, the path in which the fixing end E1 and the coupling end E2of the fixing strip 134 a interconnect is substantially the extendingdirection. Thus, based on the appearance of the image-capturing module110, the fixing strips 134 a are neither parallel nor normal to theoptical axes A1 and A2. Moreover, the fixing strips 134 a are notparallel to one another.

Please refer to FIGS. 1B and 2. FIG. 2 is a front view of the opticallens 200 as illustrated in FIG. 1B. Each of the peripheral compensationportions 220 further has a first top flat surface 226 t and a firstbottom flat surface 226 b. The central diverging portion 210 further hasa second top flat surface 216 t and a second bottom flat surface 216 b.As illustrated in FIGS. 1B and 2, within the same peripheralcompensation portion 220, the first convex surface 224 and the firstconcave surface 222 are arranged between the first top flat surface 226t and the first bottom flat surface 226 b. Within the central divergingportion 210, the second concave surface 214 and the light incidentsurface 212 are arranged between the second top flat surface 216 t andthe second bottom flat surface 216 b.

As illustrated in FIGS. 1B and 2, two opposite flat surfaces of theperipheral compensation portions 220 are co-planar with two oppositeflat surfaces of the central diverging portion 210 respectively.Specifically, the first top flat surfaces 226 t of the peripheralcompensation portions 220 and the second top flat surfaces 216 t of thecentral diverging portion 210 are co-planar. The first bottom flatsurfaces 226 b of the peripheral compensation portions 220 and thesecond bottom flat surfaces 216 b of the central diverging portion 210are co-planar such that the optical lens 200 resembles a flat plane.

FIG. 3A is a front view illustrating the lens which is used to make theoptical lens in FIG. 2. FIG. 3B is a rear view of the lens asillustrated in FIG. 3A. Please refer to FIGS. 3A and 3B. The opticallens 200 can be formed by cutting the lens 20. The lens 20 can be madewith glass or transparent plastic material. The lens 20 has two innerconcave surfaces 21, 22 and an outer convex surface 24. The two innerconcave surfaces 21, 22 opposite to each other. The outer convex surface24 is an annularly curved surface which flanks and connected to theinner concave surface 21. Moreover, the inner concave surfaces 21, 22can be quadric surfaces such as parabolic, spherical, spheroidal orhyperboloidal surfaces.

The optical lens 200 can be made by cutting the lens 20 along the twodotted lines as shown in FIGS. 3A and 3B. After cutting along the dottedlines, the lens 20 is correspondingly formed with the first top flatsurface 226 t and the second top flat surface 216 t along one of thedotted lines, and the lens 20 is correspondingly formed with the firstbottom flat surface 226 b and the second bottom flat surface 216 b alongthe other dotted line (Please refer to FIG. 2). Moreover, the dottedlines are straight lines as shown in FIGS. 3A and 3B. Thus, after thelens has been cut, the first top flat surface 226 t and the second topflat surface 216 t are flush with each other, and the first bottom flatsurface 226 b and the second bottom flat surface 216 b are flush witheach other.

After the cutting of the lens 20, three portions are defined, and themiddle portion of the lens 20 is retained as the optical lens 200 (notlabeled in FIGS. 3A and 3B). A portion of the inner concave surface 21is formed as the second concave surface 214 of the central divergingportion 210, portions of the outer convex surface 24 are formed as thefirst convex surfaces 224 of the peripheral compensation portions 220,and portions of the inner concave surface 22 are formed as the lightincident surface 212 of the central diverging portion 210 and the firstconcave surface 222 of the peripheral compensation portions 220. Thus,the first convex surfaces 224 are arranged on the same convex surface 24and the first concave surfaces 222 and the light incident surface 212are arranged on the same concave surface 22 as shown in FIGS. 3A and 3B.

FIG. 4 is a top view of the image-capturing device as illustrated inFIG. 1A after the disassembly of the casing. Please refer to FIG. 4A,the light-emitting unit 120 can emit a light beam L1. The optical axisof the light beam L1 is substantially the same as the optical axis A1 ofthe light-emitting unit 120. The light beam L1 has a plurality of lightrays L11 and L12 (L11 and L12 are only example light rays whichdemonstrates the traveling path of the light rays emitted from thelight-emitting unit, but are not limited to only two light rays L11 andL12). When the light-emitting unit 120 emits the light beam L1, thelight ray L11 sequentially passes through the first concave surface 222and then the first convex surface 224, and the light ray L12sequentially passes through the light incident surface 212 and then thesecond concave surface 214.

Since the peripheral compensation portions 220 has the negative valuedfirst focal length and the central diverging portion 210 also has thenegative valued second focal length, the peripheral compensationportions 220 and the central diverging portion 210 can spread the lightbeam L1. In other words, the peripheral compensation portions 220 andthe central diverging portion 210 can deviate the traveling directionsof the light rays L11 and L12 from the optical axis A1. Moreover, theabsolute value of the first focal length of the peripheral compensationportions 220 can be larger than the absolute value of the second focallength of the central diverging portion 210.

Since the peripheral compensation portions 220 and the central divergingportion 210 can deviate the traveling directions of the light rays L11and L12 from the optical axis A1, the optical lens 200 can spread thelight beam L1 such that the spread angle of the light beam L1 isincreased. As a result, the optical lens 200 can reduce the lightintensity of the light beam L1 along the optical axis A1 and regionsproximate to the optical axis A1. The optical lens 200 can also increasethe light intensity of the light beam L1 regions distal to the opticalaxis A1 such that the light intensity of the light beam L1 can bedistributed relatively uniform.

Furthermore, the optical axis A2 of the image-capturing lens 112 (pleaserefer to FIGS. 1A and 1C) and the optical axis A1 are substantiallyparallel. The optical axes A1 and A2 both pass through the lightincident surface 212 and the second concave surface 214 in sequence.Therefore, according to the principle of optical reversibility, theoptical lens 200 can increase the view angle of the image-capturing lens112 such that the image-capturing lens 112 may have a relatively largerview angle for capturing images, and further increase the field of view(FOV) of the image-capturing lens 112.

Notably, FIG. 4 is a top view of the image-capturing device 100 (afterthe disassembly of the casing 130), which is to view the image-capturingdevice 100 from angle above and normal to the horizontal plane. As aresult, the first top flat surface 226 t and the second top flat surface216 t are substantially parallel with the horizontal plane. In theinstant embodiment, the common plane in which the optical axis A1 of thelight-emitting unit 120 and the optical axis A2 of the image-capturinglens 112 reside is normal to the horizontal plane. In theimage-capturing device 100 as shown in FIG. 4, the optical axis A1almost completely overlaps the optical axis A2 viewing from the top.Thus, the origin and direction of the optical axis A1 is identical tothe optical axis A2 of the same as shown in FIG. 4.

Moreover, based on the various possibilities of surface designs (forexample: surfaces of different curvatures and/or surfaces of differentshapes, such as parabolic, spherical, spheroidal, or hyperboloidal, ofthe first concave surfaces 222, first convex surfaces 224, lightincident surface 212 and/or the second concave surface 214) for thefirst concave surface 222, first convex surface 224, the light incidentsurface 212 and the second concave surface 214, the optical lens 200 canchange the distribution of light intensity of the light beam L1 and theview angle of the image-capturing lens 112. Thus, the preferreddistribution of light intensity of the light beam L1 and the field ofview of the image-capturing lens 112 are provided such that variousoptical needs can be satisfied.

FIG. 5 is a top view of the optical touch system illustrating anembodiment of the instant disclosure. Please refer to FIG. 5, theoptical touch system 300 includes a panel 330, a plurality of theaforementioned image-capturing devices 100, a plurality of initialimage-capturing devices 310, a processing unit 320 and a plurality ofreflective strips 340. The panel 330 has a flat surface which can beviewed from above the panel 330 as shown in FIG. 5. In other words, FIG.5 shows the flat surface of the panel 330. The panel 330 can be adisplay panel, a transparent board (for example: glass board or plasticboard), or opaque board. The display panel can be a liquid crystaldisplay panel (LCD panel), and the optical touch system 300 can be usedas a touch display screen or a touch pad without any screen displayfunctionality.

The panel 330 is substantially a rectangular shaped panel, and the flatsurface of the panel 330 can resemble a rectangular such that the flatsurface of the panel 330 has four straight edges. The image-capturingdevice 100 and the initial image-capturing devices 310 are arranged onthe periphery of the panel, and the reflective strips 340 are arrangedon the straight edges.

In FIG. 5, the total quantity of the image-capturing devices 100 and theinitial image-capturing devices 310 of optical touch system 300 totalsto seven. Four initial image-capturing devices 310 are respectivelyconfigured at four corners of the flat surface of the panel 330, andthree image-capturing devices 100 are configured at one of the straightedges. In other words, two initial image-capturing devices 310 and threeimage-capturing devices 100 are configured at the same edge.

The initial image-capturing device 310 is substantially animage-capturing device 100 before the assembly of the optical lens 200and the casing 130. Thus, the initial image-capturing devices 310 mayinclude the image-capturing module 110 and the light-emitting unit 120,but not include the optical lens 200 and the casing 130. However,although the initial image-capturing device 310 may not include theoptical lens 200, the initial image-capturing device 310 can alsoinclude other types of optical elements different from the optical lens200. When the optical touch system 300 is in operation, the initialimage-capturing device 310 and the image-capturing device 100 emit thelight beam L1 (not drawn in FIG. 5, please refer to FIG. 4). The lightbeam L1 is transmitted via the flat surface of the panel 330 andreflected by the reflective strips 340. When a finger, a stylus or asimilar object touches the panel 330, a part of the light beam L1 willbe blocked, and shadows are formed on the bezel (such as the reflectivestrips 340) of the panel 330

At the same time, the initial image-capturing device 310 and theimage-capturing module 110 of the image-capturing device 100 willcapture image data of the objects (not shown in FIG. 5), which is theimages of the shadows. Then, image signals corresponding to the imagesof the shadows are generated. The processing unit 320 receives the imagesignals generated by both the initial image-capturing devices 310 andthe image-capturing devices 100. Then, the processing unit 320 generatescorresponding coordinate signals in order to provide touch function.Moreover, the processing unit 320 can be a microcontroller or a centralprocessing unit (CPU).

The image-capturing module 110 of the image-capturing device 100 has afirst view angle V1, and the initial image-capturing device 310 has aninitial view angle V4. Since the initial image-capturing device 310 maybe the image-capturing device 100 without assembly of the optical lens200 and the casing 130, the initial view angle V4 is equal to the firstview angle V1. The optical lens 200 can change the spread angle of thelight beam L1 and the initial view angle of the image-capturing lens 112(please refer to FIG. 4). Thus, the optical lens 200 can change thefirst view angle V1 such that the field of view of the initialimage-capturing device 310 is different from the field of view of theimage-capturing device 100.

Since the initial image-capturing device 310 and the image-capturingdevice 100 have different field of views, the overall field of viewcoverage of all the initial image-capturing devices 310 and theimage-capturing devices 100 can be enhanced. In other words, the range,where a finger, stylus, or similar object is detected on the flatsurface of the panel 330 by all of the initial image-capturing devices310 and the image-capturing devices 100, is enhanced. As a result, thetouch control quality of the optical touch system 300 is enhanced.

Moreover, with various designs of the first concave surfaces 222, thefirst convex surface 224, the light incident surface 212 and the secondconcave surface 214, the optical lens 200 can change the light intensitydistribution of the light beam L1 and the field of view of theimage-capturing lens 112. Thus, by using two optical lenses 200 ofdifferent designs, the optical touch system 300 has the image-capturingdevice 100 with two or more various field of views in order to becompatible with optical touch systems of various types or standards. Asa result, the design of at least two optical lenses of theimage-capturing devices 100 may be different such that the fields ofview of the two image-capturing devices 100 are different.

Taking FIG. 5 as an example, the design of all the optical lens 200 ofthe optical touch system 300 is not necessarily the same. The opticallens 200 can change the first view angle V1 to the second view angle V2(illustrated as the image-capturing devices 100 on the left and right inFIG. 5), and other optical lenses 200 can change the first view angle V1to the third view angle V3 (illustrated as the center image-capturingdevice 100 in FIG. 5). The second view angle V2 and the third view angleV3 are substantially larger than the first view angle V1. The secondview angle V2 is not equal to the third view angle V3. Thus, by using atleast two optical lenses 200 of different designs, the image-capturingdevice 100 can have various view angles and be compatible with opticaltouch systems of various types or standards.

Please refer to the optical touch system 300 as shown in FIG. 5. Thetotal quantity of the image-capturing device 100 and the initialimage-capturing device 310 totals to seven, in which four being theinitial image-capturing devices 310, and three being the image-capturingdevices 100. However, in other embodiments, the total quantity of theimage-capturing device 100 and the initial image-capturing device 310can be totaled from two to six, or more than seven.

Moreover, the image-capturing device 100 can only be one such that theoptical lens 200 can only be one. The initial image-capturing device 310can be one or more than one. Furthermore, the optical touch system 300can only include image-capturing device 100 or devices 100 and notinclude any initial image-capturing device 310. In other words, all ofthe image-capturing devices 100 of the optical touch system 300 includethe optical lenses 200. The quantity and configuration of theimage-capturing devices 100 and the initial image-capturing devices 310of the optical touch system 300 are only exemplary and are not limitedhereto.

In summary, the optical lens of the instant disclosure can change theview angle of the image-capturing device which can be applied to theoptical touch system. Thus, the optical touch system can apply theaforementioned lens to change the field of view of the image-capturingdevice in order to enhance the overall detectable range for objects ofall image-capturing devices. As a result, the touch control quality ofthe optical touch system can be further enhanced. Moreover, the opticallens of the instant disclosure can also change the light intensitydistribution of the light-emitting unit such that the light intensity ofthe light beam which is emitted from the light-emitting unit can bedistributed relatively even, and the probability of overexposure orunderexposure is reduced.

The figures and descriptions supra set forth illustrated the preferredembodiments of the instant disclosure; however, the characteristics ofthe instant disclosure are by no means restricted thereto. All changes,alternations, combinations or modifications conveniently considered bythose skilled in the art are deemed to be encompassed within the scopeof the instant disclosure delineated by the following claims.

What is claimed is:
 1. An optical lens used for configuring in front ofan image-capturing lens of an image-capturing device, which includes alight-emitting unit used for emitting a light beam, the optical lenscomprising: a pair of peripheral compensation portions each having afirst convex surface and a first concave surface arranged opposite tothe first convex surface; and a central diverging portion arrangedbetween and connected to the peripheral compensation portions, thecentral diverging portion having a second concave surface and a lightincident surface arranged opposite to the second concave surface, thesecond concave surface arranged between the first convex surfaces, thelight incident surface arranged between the first concave surfaces,wherein the optical axis of the light beam sequentially passes throughthe light incident surface and the second concave surface, and aplurality of light rays of the light beam passes through the firstconcave surfaces and the first convex surfaces in sequence.
 2. Theoptical lens as recited in claim 1, wherein the peripheral compensationportions each further has a first top flat surface and a first bottomflat surface, the first convex surface and the first concave surface arearranged between the first top flat surface and the first bottom flatsurface, the central diverging portion further has a second top flatsurface and a second bottom flat surface, and the second concave surfaceand the light incident surface are arranged between the second top flatsurface and the second bottom flat surface.
 3. The optical lens asrecited in claim 2, wherein the first top flat surface and the secondtop flat surface are co-planar surfaces, and the first bottom flatsurface and the second bottom flat surface are co-planar surfaces. 4.The optical lens as recited in claim 1, wherein the light incidentsurface is a concave surface.
 5. The optical lens as recited in claim 4,wherein the curvature of the light incident surface is larger than thecurvature of the second concave surface.
 6. The optical lens as recitedin claim 1, wherein the curvature of the first convex surface is smallerthan the first concave surface.
 7. The optical lens as recited in claim1, wherein each of the peripheral compensation portions has a firstfocal length, and the central diverging portion has a second focallength, wherein the first focal length and the second focal length areless than zero, and the absolute value of the first focal length islarger than the absolute value of the second focal length.
 8. Theoptical lens as recited in claim 1, wherein the optical lens facilitatesthe light beam to spread and to travel towards the second concavesurface.
 9. The optical lens as recited in claim 1, wherein the firstconvex surfaces are arranged on the same convex surface, and the firstconcave surfaces are arranged on the same concave surface.
 10. Theoptical lens as recited in claim 1, wherein the peripheral compensationportions and the central diverging portion are integrally formed.
 11. Animage-capturing device, comprising: an image-capturing module comprisingan image-capturing lens; a light-emitting unit fixed at theimage-capturing module and emitting a light beam; an optical lens,comprising: a pair of peripheral compensation portions each having afirst convex surface and a first concave surface arranged opposite tothe first convex surface; and a central diverging portion arrangedbetween and connected to the peripheral compensation portions, thecentral diverging portion having a second concave surface and a lightincident surface arranged opposite to the second concave surface, thesecond concave surface arranged between the first convex surfaces, thelight incident surface arranged between the first concave surfaces,wherein the optical axis of the light beam and the optical axis of theimage-capturing lens both pass through the light incident surface andthe second concave surface in sequence, and a plurality of light rays ofthe light beam passes through the first concave surfaces and the firstconvex surfaces in sequence; and a casing, comprising: a frame housingthe optical lens and exposing the first concave surfaces, the firstconvex surfaces, the light incident surface and the second concavesurface; and a fixing member connected to the frame and fixing theimage-capturing module.
 12. The image-capturing module as recited inclaim 11, wherein the fixing member comprises a pair of fixing strips,and the image-capturing module is fixed between the fixing strips. 13.The image-capturing module as recited in claim 11, wherein each of thefixing strips has a fixing end and a coupling end opposite to the fixingend, the coupling end connected to the frame, and the image-capturingmodule is fixed between the fixing ends.
 14. The image-capturing moduleas recited in claim 13, wherein the frame has a light entering openingand a light exiting opening corresponding to the light entering opening,the light entering opening arranged between the coupling ends exposesthe first concave surfaces and the light incident surface, whereas thelight exiting opening exposes the first convex surfaces and the secondconcave surface.
 15. The image-capturing module as recited in claim 12,wherein each of the fixing strips extends in a direction neitherparallel nor normal to the optical axis of the light beam.
 16. Anoptical touch system, comprising: a panel having a flat surface; aplurality of image-capturing devices configured at the periphery of thepanel, each comprising; an image-capturing module comprising animage-capturing lens for capturing at least one image data of an objectdisposed on the flat surface to generate a corresponding image signal; alight-emitting unit fixed at the image-capturing module and emitting alight beam; an optical lens, comprising; a pair of peripheralcompensation portions each having a first convex surface and a firstconcave surface arranged opposite to the first convex surface; and acentral diverging portion arranged between and connected to theperipheral compensation portions, the central diverging portion having asecond concave surface and a light incident surface arranged opposite tothe second concave surface, the second concave surface arranged betweenthe first convex surfaces, the light incident surface arranged betweenthe first concave surfaces, wherein the optical axis of the light beamand the optical axis of the image-capturing lens both passes through thelight incident surface and the second concave surface in sequence, and aplurality of light rays of the light beam passes through the firstconcave surfaces and the first convex surfaces in sequence; and aprocessing unit receiving the image signal and generating a coordinatesignal corresponding to at least one object.
 17. The optical touchsystem as recited in claim 16, wherein the shape of the flat surface issubstantially rectangle and at least two of the image-capturing devicesare configured at least two corners of the flat surface respectively.18. The optical touch system as recited in claim 17, wherein the flatsurface has a straight edge and at least three of the image-capturingdevices are configured at the straight edge.
 19. The optical touchsystem as recited in claim 16, wherein the panel is a display panel. 20.The optical touch system as recited in claim 16, wherein the panel is anopaque panel.
 21. The optical touch system as recited in claim 16,wherein the image-capturing module has a first view angle, the opticallens of one of the image-capturing devices changes the first view angleto a second view angle, the optical lens of another one of theimage-capturing devices changes the first view angle to a third viewangle, wherein the second view angle and the third view angle are largerthan the first view angle, and the second view angle is not equal to thethird view angle.
 22. An optical touch system, comprising: a panelhaving a flat surface; at least one initial image-capturing deviceconfigured at the periphery of the panel; at least one image-capturingdevice configured at the periphery of the panel, comprising; animage-capturing module comprising an image-capturing lens for capturingat least one image data of an object disposed on the flat surface togenerate a corresponding image signal, wherein the image-capturingmodule has a first view angle; a light-emitting unit fixed at theimage-capturing module and emitting a light beam; an optical lenschanging the first view angle and comprising; a pair of peripheralcompensation portions each having a first convex surface and a firstconcave surface arranged opposite to the first convex surface; and acentral diverging portion arranged between and connected to theperipheral compensation portions, the central diverging portion having asecond concave surface and a light incident surface arranged opposite tothe second concave surface, the second concave surface arranged betweenthe first convex surfaces, the light incident surface arranged betweenthe first concave surfaces, wherein the optical axis of the light beamand the optical axis of the image-capturing lens both pass through thelight incident surface and the second concave surface in sequence, and aplurality of light rays of the light beam passes through the firstconcave surfaces and the first convex surfaces in sequence.
 23. Theoptical touch system as recited in claim 22, wherein the initialimage-capturing device has an initial view angle which is equivalent tothe first view angle.
 24. The optical touch system as recited in claim22, wherein the quantity of the image-capturing device is multiple, andthe plurality of image-capturing devices is configured at the peripheryof the panel.
 25. The optical touch system as recited in claim 24,wherein the optical lens of one of the image-capturing devices changesthe first view angle to a second view angle, the optical lens of anotherimage-capturing device changes the first view angle to a third viewangle, the second view angle and the third view angle are larger thanthe first view angle, and the second view angle is not equal to thethird view angle.